Would You Recognize A Holotype If It Hit You in the Chevron?
ere’s atrick question: What’s the ampleof a species known atthe time be availableas a basis of comparison difference between the “type of original publication.” In other and standard of reference for any Hspecimen” and the “holotype “of a words, a holotype or type specimen future finds. Is this specimen I’ve species? The question is tricky be- is the physical specimen upon which found of the same species? Check cause the two terms refer to exactly a taxon (generally but not always a the description of the holotype and, the same thing. genus or species) is established—or, if possible,the actual specimen itself. In understanding what paleon- in the jargon, “erected.” And how about another term, as tologists and other scientists mean Holotypes are meant to be long as we’re throwing them out: when they use these words, the defi- registered and deposited with a paratype. Paratypes are specimens nition from the Oxford English Dic- museum or institution where, at identical to the holotype and included tionary is a good place to start: “A least in theory, they can be consulted in the “type series” by the author in specimen chosen as the basis of the by others. Institutions are typically the original publication of the new first description of a new spe- taxon. (Botany has somewhat cies.”The OED dates the first use different rules for the use of the of the word to an article by the RECENT ISSUES term “paratype,” however.) So, if famous invertebrate paleontolo- a paleontologist collected five gist, Charles Schuchert (1858- IN PALEONTOLOGY specimens of the same species 1942), director of the Peabody of a brand-new brachiopod she Museum of Natural History at Yale identified by a code (YPB is the Yale wanted to name, and mentioned University from 1904-1923, the first Peabody Museum,FMNH isthe Field themall aspart of the series of speci- president of the Paleontological So- Museum, and BHI is the Black Hills mens examined, one would become ciety, and an avid fossil-hound who Institute—as in BHI 3033, the the holotype and the other four amassed one of the largest brachio- Tyrannosaurus illustrated by Fabio would be paratypes. pod collections in the world. Pastori in this issue).1 So far so good. Unfortunately, it In April 1897, Schuchert wrote in This institution code is followed turns out that things are a littlemore Science: “A holotype in natural his- by numbers or letters that identify complicated than that. tory is a particular individual delib- the specific specimen in the Currently, a mini-debate has erately selected by the author of a institution’s collections, allowing the erupted over whether holotype must species, or it may be the only ex- holotype—again theoretically—to always mean the original specimen
Chevrons are a series of bones on the underside of the tail of many reptiles (as well as some mammals). Pictured is a replica of an eleven-inch specimen of a Diplodocus chevron. Fossil News – Fall 2017 37 upon which a taxon is erected,or whether the definition sil animals. As a result, many dinosaurian spe- should be “loosened” to encompass the specimen that cies were named on the basis of non-diagnostic best represents or is most diagnostic of the species. remains.... Despite being one of the most com- The problem for paleontology—and especially for ver- pletely known of all dinosaurs, and among those tebrate and dinosaurian paleontology—becomes almost best known to the general public, Diplodocus suf- instantly obvious. In the case of specimens that tend to be fers badly from this syndrome. It was founded by described as wholeentities—an echinoid,an insect (fossil Marsh on a non-diagnostic fragmentary speci- or not),an extantbird—the holotype isvirtuallyalways the men (YPM 1920), which supposedly functions as entireorganism or,at least,itscompletefossilized remains. the type specimen of the type species, D. longus. But when a new dinosaurian species isestablished on the basis of a few scattered vertebrae or a tooth, what hap- The petition’s authors themselves argued that penswhen laterworkersdiscovera femuror apartialskull? “Diplodocus shouldnot be typified by an undiagnosable How can they compare the holotype to these discoveries type species,” and that “the undiagnosable state of the and come to any useful conclusions? holotype of D. longus (YPM 1920, a partial tail and a The doubt thatarises spontaneously,of course, is this: chevron)” is good reason to replace it with “the much Doesn’t this suggest that a certain number of described better represented [CM 84 specimen of ] D. carnegii dinosaurs species may be invalid? In other words, Hatcher, 1901. CM 84, they go on to say, is a “well-pre- couldn’t partial remains sometimes be assigned to sepa- served and mostly articulated specimen,” casts of which rate species even when they might, in fact, have come “are on display in various museums around the world.” from the same kind of organism? And the spontaneous Citizen scientist Mickey Mortimer, however, curator answer to both questions is: Yes. of the Theropod Database Blog (theropoddatabase. At the heart of the current con- blogspot.com), opposes the petition, arguing that troversy is a 2016 petition by the ICZN codein no way requires the holotype to Tschopp and Mateus that be diagnostic, meaning that it need not be the best-preserved or best-described specimen.Asa technicalmatter,that asked the In- statement is true enough: ternational Com- The ICZN code doesn’t mission on Zoological require it. But should it? Nomenclature (ICZN) to desig- Holotypes are nate a different specimen of some-times lost, Diplodocus carnegii, aJurassic mem- ber of the group of giant dinosaurs known as Diplodocids, named for the distinctive “double-beamed” destroyed in fires or natural disasters, or never de- chevron bones on the ventral posited in the first place and, in those cases, there surface of their tails, asthe holotype rarely appears to be much argument over replacing of the species. them with what are termed “neotypes.” In the case University of Bristol (UK) paleontologist Michael P. of Diplodocus and the 2016 petition, however, there are Taylor,who curates the Sauropod Vertebra Picture of the deeper questions of whether dinosaurs “deserve spe- Week Blog (svpow.com), not only supports the petition, cial treatment,”as Taylor has written, precisely because he goes even further, saying that the “ICZN was never they are “in many cases ... represented by eroded and designed with dinosaurs in mind in the first place” distorted fossils of a tiny part of the animal [and are (Taylor, 2016a). The problemwith the current Diplodocus thus] already an aberration from the perspective of the holotype, as Taylor explained in his formal statement to ICZN” (Taylor, 2016b). the ICZN in support of the change, As of this writing, nearly 120 cases remain open be- fore the ICZN, from arachnids to brachiopods, lemurs to is a familiar one to dinosaurian workers: when sponges, but Diplodocus isn’t among them. In fact, Case working with very large animals that died many 3700 is entirely missing from its database. Perhaps the millions of years ago, most specimens are incom- fundamental question raised by the Tschopp and Mateus plete, and often very uninformative.... [This]issue petition—what exact function a holotype is meant to was greatly exacerbated by the “Bone Wars” of E. serve—is giving the committee pause. D. Cope and O. C. Marsh, rival palaeontologists in the late 19th century of the USA, who each aimed —Wendell Ricketts to outdothe other by naming more species of fos- 38 Fossil News – Fall 2017 References Taylor, Michael P. (2016a). Comment on the Pro- posed Designation of Diplodocus carnegii Hatcher, 1901 As the Type Species of Diplodocus Marsh, 1878. (Case 3700; see BZN 73: 17-24).
Note 1 Anyone geeking out over the curation of natural-his- tory collections should consult the database of more than 7,000 institutions and their codes maintained by GRBio, the Global Registry of Biodiversity Repositories: http://grbio.org/find-biorepositories.
[Facing page: Illustration of Diplodocus carnegii by Dmitry Bogdanov ([email protected]); used via a Cre- ative Commons CC BY 3.0 license.]
Fossil News – Fall 2017 39